Device for assembling and dismantling a fuel injection valve

ABSTRACT

An assembling device for assembling and disassembling of a fuel injector ( 3 ) in a mounting hole ( 3 ) of a cylinder head in an internal combustion engine has at least two contact surfaces engaging in the fuel injector. A hold-down surface is formed on each elastic contact element to transmit a hold-down force to the fuel injector and a locking recess in which a locking projection of the fuel injector engages to transmit a disassembling force to the fuel injector.

FIELD OF THE INVENTION

The present invention relates to a mounting (also referred to asassembling) device for mounting and removing (also referred to asdisassembling) a fuel injector, in particular a high-pressure directinjector, into and from a mounting bore in a cylinder head of aninternal combustion engine. Fuel is injected directly into thecombustion chamber of the internal combustion engine through thishigh-pressure direct injector.

BACKGROUND INFORMATION

An assembling device having a main body at least partially surroundingthe fuel injector is described in German Patent Application No. 197 05990 A1, collar section directed inward is formed at a first end of themain body, and a collar section directed outward is formed at a secondend of the main body, opposite the first end. While the collar sectiondirected radially inward can be inserted into a groove of the fuelinjector, the collar section directed outward protrudes outward from themounting opening of the fuel injector. An appropriate tool, for example,an assembly iron, can engage the mounting hole of the cylinder head inorder to lift the assembling device together with the fuel injector fromthe mounting hole.

This conventional assembling device is not suitable for transmitting ahold-down force to the fuel injector to counteract the combustionpressure in the combustion chamber of the internal combustion engine.Therefore, the fuel injector is held down via a separate hold-downdevice or the fuel injector is only secured in the mounting hole byfriction. The collar section protruding inward can, however, transmit apressure force to the fuel injector to press the fuel injector into themounting hole. For this purpose, the collar section protruding inwardengages in a corresponding groove in the fuel injector. Thedisadvantage, however, is that this pressure force does not act at thecenter and symmetrically with the central axis of the fuel injector, butin a rather one-sided manner. Furthermore, ease of handling of theassembling device when inserting the fuel injector is subject toimprovement.

U.S. Pat. No. 4,561,159 describes a disassembling device for a dieselinjection nozzle. An end area of the fuel injector opposite the sprayorifice can be inserted at the side into a slit in the disassemblingdevice. The disassembling device is not inserted into the mounting boreof the cylinder head and it does not remain in the mounting bore whenassembled. The disassembling device described in U.S. Pat. No. 4,561,159is instead a tool extension that is attached to the fuel injector beforedisassembling the fuel injector. No hold-down force is transmitted tothe fuel injector. Connecting the disassembling device to the fuelinjector is a relatively complicated process.

The assembling device according to the present invention having thecharacterizing features of claim 1 advantage over the conventionaldevices that the two contact elements apply a centered and symmetricalhold-down force to the fuel injector, so that an oblique position ortipping of the fuel injector is avoided. The locking connection betweenthe assembling device and the fuel injector considerably improveshandling when inserting the fuel injector into the assembling device.The fuel injector is inserted into the assembling device axially, ratherthan laterally, which can be better controlled, especially in partiallyor fully automated production.

If at least two diametrically opposite contact sections are provided,the hold-down force, as well as the disassembling force, are introduced,to a considerable degree, centrally and symmetrically to the centralaxis of the fuel injector.

The locking projections formed on the fuel injector have, for example, ataper facing away from the hold-down surfaces. The taper helps thelocking projections engage the locking recesses provided on the contactelements.

The assembling device is guided, for example, into the mounting holewith a slight clearance in order to ensure accurate axial alignment ofthe assembling device with respect to the mounting hole even if theinternal combustion engine installed in a vehicle, for example, issubjected to a jarring motion.

A recess for the connecting plug of the fuel injector is advantageouslyprovided between the contact elements, so that the connecting plug of afuel injector mounted on the assembling device is arranged between thecontact elements.

The assembling device can be economically manufactured by deep drawingfrom a metal sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an injection side of an embodiment of an assembling deviceaccording to the present invention, a fuel injector inserted into theassembling device according to the present invention, and a partialsection of a cylinder head.

FIG. 2 shows a top view of the injection-side end of the embodiment ofan assembling device according to the present invention illustrated inFIG. 1.

FIG. 3 shows a side view of the injection-side end of the embodiment ofthe assembling device according to the present invention illustrated inFIG. 1.

FIGS. 4A-4D show an exemplary sequential extension of the assemblingdevice and the fuel injector according to the present invention, beingremoved from a mounting hole.

DETAILED DESCRIPTION

FIG. 1 illustrates the injection side of an embodiment of assemblingdevice 1 according to the present invention. Fuel injector 2 is insertedinto assembling device 1 according to the present invention. Assemblingdevice 1 and fuel injector 2 are inserted into a mounting hole 3 of acylinder head 4 of an internal combustion engine. Fuel injector 2 is ahigh-pressure direct injection valve for directly injecting fuel intothe combustion chamber of the internal combustion engine.

Mounting hole 3 of cylinder head 4 is divided into a widened section 5,a narrowed section 6, and a conical section 7 that connects widenedsection 5 to narrowed section 6. An injection section 8 of fuel injector2 is located in narrowed section 6 of the mounting hole 5.

Fuel injector 2 must be held down in mounting hole 3 of cylinder head 4against the combustion pressure in the combustion chamber. Holding downfuel injector 2 in mounting hole 3 of cylinder head 4 is one of the twofunctions of assembling device 1 according to the present invention. AsFIG. 1 shows, assembling device 1 according to the present inventionhas, at its injection side end, two contact elements 9 and 10, which arearranged diametrically opposite one another. Assembling device 1 mayalso have more than two contact elements, for example, three or fourcontact elements, which are, arranged, for example, peripherally evenlydistributed. Each of the two contact elements 9 and 10 has a fronthold-down surface 11 and 12, which engages in an annular countersurfaceof a housing body 14 of fuel injector 2 in order to hold down fuelinjector 2 against the combustion pressure in the combustion chamber.Fuel injector 2 is held at a conical section 15 against conical section6 of mounting hole 3 by the hold-down force of assembling device 1. Dueto the conical design of a section of mounting hole 3 and fuel injector2, accurate alignment of fuel injector 2 with respect to central axis 16of mounting hole 3 is guaranteed.

The two contact elements 9 and 10 are connected to a main body (notshown in FIG. 1), which surrounds fuel injector 2 preferably in anannular shape. A fastening section (also not illustrated) of the mainbody protrudes from mounting hole 3 of cylinder head 4 and can befastened to cylinder head 4. The area of the fastening section can beadjusted to the specific geometric configuration of cylinder head 4. Thehold-down force can be exerted onto assembling device 1 by the mountingscrews provided on the fastening section, for example.

Fastening device 1, for example, has very small play with respect tomounting hole 3 of cylinder head 4, so that assembling device 1 isaccurately guided in mounting hole 3, and fuel injector 2 is accuratelyaligned axially even under rough conditions, for example, in the eventof a jarring motion.

The two contact elements 9 and 10 also have two locking recesses 17 and18, which in the present embodiment are closed on all sides. Lockingrecesses 17 and 18 have a rectangular cross section in the presentembodiment. Locking projections 19, 20, radially formed on fuel injector2, can be inserted into locking recesses 17 and 18, respectively, bypushing fuel injector 2 into assembling device 1 in the axial direction.

Locking projections 19 and 20 for example, have tapers 21 and 22 facingaway from hold-down surfaces 11 and 12, which elastically supportcontact elements 9 and 10 radially outward when fuel injector 2 isinserted. As soon as locking projections 19 and 20 fully engage withlocking recesses 17 and 18, contact elements 9 and 10 retractelastically, so that fuel injector 2 is secured on contact elements 9and 10 via locking projections 19 and 20. Fuel injector 2 is fastened toassembling device 1 prior to inserting fuel injector 2 and assemblingdevice 1 into mounting hole 3 of cylinder head 4. After assemblingdevice 1 has been inserted into mounting hole 3, assembling device 1,due to its small play with respect to mounting hole 3, is securedagainst radial separation of contact elements 9 and 10 and loosening oflocking projections 19 and 20.

FIGS. 4A-4D illustrate the extension of the assembling device 1 and fuelinjector 2 during disassembly. Locking projections 19 and 20 havecontact surfaces 23 and 24, respectively, on which a countersurface 25,26 formed on contact element 9, 10 engages during disassembly.Therefore, when assembling device 1 is pulled out of mounting hole 3,fuel injector 2 is also pulled out axially, being pulled out of mountinghole 3 as shown sequentially in FIGS. 4A-4D.

Mounting fuel injector 1 on assembling device 1 is considerablyfacilitated by the snap-in connection formed by locking recesses 17 and18, and locking projections 19 and 20, which substantially improveshandling. Fuel injector 2 is brought to assembling device 1 notlaterally, but in the axial direction, which may be of a considerableadvantage in automatic manufacturing.

FIG. 2 shows the embodiment of assembling device 1 illustrated in FIG. 1as a top view onto the injection-side end, i.e., from below in FIG. 1.The two contact elements 9 and 10 can be seen, hold-down surfaces 11 and12 being provided with cross-hatching for greater clarity in FIG. 2.Furthermore, locking recesses 17 and 18 can be seen in both contactelements 9 and 10. A recess 30 and 31 is located between the twodiametrically opposite contact elements 9 and 10, with at least one ofthe two recesses 30 and 31 having a width such that a connecting plug offuel injector 2 can be received by this recess 30 and 31. The connectingplug is arranged, after fuel injector 2 is secured on fastening device1, between the two contact elements 9 and 10.

The two contact elements 9 and 10 are elastically connected to a mainbody 32 extending between the two contact elements 9 and 10 against thedirection of injection or are designed in one piece with main body 32.Main body 32, for example, surrounds fuel injector 2 on all sides as aring.

FIG. 3 shows a side view of the embodiment of assembling device 1illustrated in FIGS. 1 and 2 to better elucidate the present invention.One of the two contact elements 9 and locking recess 17, which isrectangular in this embodiment are shown here.

What is claimed is:
 1. A mounting device for mounting and removing afuel injector in a mounting hole of a cylinder head of an internalcombustion engine, the assembling device comprising: at least onecontact element configured to act upon the fuel injector and to apply ahold-down force to hold down the fuel injector in the mounting hole anda removing force to remove the fuel injector, the at least one contactelement including at least two elastic contact elements having ahold-down surface and a locking recess, the hold-down surface beingconfigured to transmit the hold-down force to the fuel injector, thelocking recess being configured to engage a locking projection of thefuel injector to transmit the removing force to the fuel injector. 2.The device according to claim 1, wherein: two diametrically oppositecontact elements are provided.
 3. A device according to claim 1,wherein: the at least one contact element is axially adjacent to a mainbody of the mounting device and radially elastically connected to themain body.
 4. The device according to claim 3, wherein: the main bodyhas a fastening section configured to protrude from the mounting holeand to fasten the cylinder head.
 5. The device according to claim 1,wherein: the locking projection formed on the fuel injection has a taperfacing away from the hold-down surface.
 6. The device according to claim1, wherein: the locking recess is enclosed on all sides and has ansubstantially rectangular cross section.
 7. The device according toclaim 1, wherein: the device is configured to be guided into themounting hole with small play.
 8. The device according to claim 1,wherein: a recess for a connecting plug of the fuel injector is providedbetween the at least two elastic contact elements.
 9. The deviceaccording to claim 1, wherein: the device is manufactured from sheetmetal by deep drawing.